1. Technical Field
The disclosure relates to a capsule medical device introduced into an organ of a subject, such as a patient, to obtain information about the subject.
2. Related Art
In endoscopes, a capsule endoscope is known which has an imaging function, a wireless communication function, and the like in a capsule-shaped casing formed in a sufficient size to be introduced into a digestive tract of a subject, such as a patient. This capsule endoscope is swallowed from a mouth of the subject, successively imaging inside the subject to generate image signals while moving in the digestive tract or the like by peristalsis or the like, and wirelessly transmits the image signals to a receiving device outside the subject. The receiving device is carried by the subject, receives in-vivo images wirelessly transmitted by the capsule endoscope introduced into an internal organ of the subject, and stores the received in-vivo images in a recording medium. The in-vivo images stored in the recording medium of the receiving device are captured into an image display device of a workstation or the like. The image display device displays an in-vivo image group of the subject obtained through the recording medium. A doctor, a nurse, or the like observes the in-vivo images displayed on the image display device to diagnose the subject.
The capsule endoscope has a configuration in which a capsule-shaped casing includes a transparent optical dome (transparent casing) and a cylindrical body portion (cylindrical casing) where the transparent optical dome is mounted to an end portion of the cylindrical body portion on a side of an opening of the cylindrical body portion, and the capsule-shaped casing incorporates an illumination unit such as LEDs illuminating inside an organ through the optical dome, an optical unit such as a lens focusing light reflected from inside an organ illuminated by the illumination unit, and an information acquisition member for acquiring information about the subject from an image sensor such as a CCD capturing an image inside an organ (i.e., in-vivo image) formed by the optical unit (e.g., see JP 5340557 B2, JP 5160698 B2, and JP 4790765 B2). Such a capsule endoscope is required to have a structure for positioning an optical pupil center of the optical unit and a spherical center of a dome portion (hemispherical portion), in order to prevent flare. Furthermore, it is necessary to reduce a wall thickness of the casing as an exterior to increase an inner space, for reduction in size and high functionality of the capsule endoscope. Still furthermore, it is desired to reduce the weight of the casing so that the capsule endoscope has a density closer to a density of a liquid inside the digestive tract, for smooth movement of the capsule endoscope in the subject. In addition, it is desired that the capsule endoscope has an outer surface of a smooth shape to facilitate swallowing by the subject.
FIG. 6 is a cross-sectional view illustrating a configuration of a main portion of a capsule endoscope disclosed in JP 5340557 B2. In a capsule endoscope 301 illustrated in FIG. 6, a positioning member 307 is provided to position an optical pupil center of an optical unit 304 and a spherical center of an optical dome portion 321, achieving reduction in wall thickness of the optical dome portion 321 and a cylindrical body portion 322 (e.g., wall thickness D3) to reduce the weight of a casing 302.
FIG. 7 is a cross-sectional view illustrating a configuration of a main portion of a capsule endoscope disclosed in JP 5160698 B2. A capsule endoscope 401 illustrated in FIG. 7 adopts a configuration in which an optical dome portion 421 of a casing 402 has a large thickness to provide abutment surfaces 421a and 421b for abutment of an end surface 422a of a cylindrical body portion 422 on the abutment surface 421a, and for abutment of an end surface 430a of a spacer 430 on the abutment surface 421b, and each member is positioned.
FIG. 8 is a cross-sectional view illustrating a configuration of a main portion of a capsule endoscope disclosed in JP 4790765 B2. A capsule endoscope 501 illustrated in FIG. 8 adopts a bonding method capable of ensuring water-tightness in a short time, in which an inner peripheral surface 521a of an optical dome portion 521 is fitted on an outer peripheral surface 522a of a cylindrical body portion 522 to be subjected to not conventional thermal bonding using a thermosetting adhesive, but UV bonding or laser welding through the optical dome portion 521 on the outside.